staging: comedi: remove inline alloc_private()

This inline function has a very generic name and it's only a
wrapper around a simple kzalloc(). Since the inline function
does not save any lines-of-code, instead of renaming it just
remove it and do the kzalloc() directly.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>